Please understand that there are two(2) Allen Magnum rounds that shoot a 270 caliber bullet. The original is the "270 Allen Magnum" which is based on a full length 300 RUM case with the shoulder angle increased and body taper reduced.
The other round is called the "277 Allen Mag". This wildcat is based on the full length 338 Lapua case necked down to 270 with increased shoulder angle and much less body taper. The "277 AM" was designed at the request of my good friend Richard Graves for the ultimate 270 cal round.
Performance is similiar with both rounds but case quality and strength are significantly better with the Lapua based round. That said, it is also significantly more involved to form cases for as well so its kind of a trade off.
If your looking for a 270 Allen Mag or 277 Allen Mag rifle you can send me an e-mail at the below address. If your looking to try some of Richards Wildcat Bullets send him an e-mail at firstname.lastname@example.org
The bullets tested in this rifle were the Wildcat 169.5 gr ULD RBBTs. A new Wildcat Bullet will be here soon which was designed speicifically for the 277 Allen Magnum but will also work equally well in the 270 Allen Mag and other large capacity 270 wildcats. This new bullet will be the 185 gr ULD RBBT.